This invention relates generally to semiconductor devices and more particularly to insulating spacers and methods of forming such spacers for use in packaging semiconductor devices.
As is known in the art, a thermally and electrically conductive package for housing a semiconductor device often includes an insulating spacer member to electrically separate a pair of electrical contacts of the semiconductor device. In a package, for example, for an IMPATT diode which has upper and lower electrical contacts, an insulating spacer member having a centrally disposed aperture and a conductive layer provided on upper and lower opposing surfaces thereof, is generally used to maintain the electrical separation between the upper and lower contacts of the IMPATT diode. The IMPATT diode is generally disposed within the aperture provided in the insulating member, with the upper and lower conductive surfaces of the insulating member providing bonding surfaces to the diode and package. The bottom contact of the IMPATT diode and the bottom conductive surface of the insulating member are each bonded to the conductive package, and the upper contact of the IMPATT diode is bonded to the upper surface of the insulating member. The conductive layers on the upper and lower surfaces of the insulating member are generally required to provide adequate thermal and electrical conductivity to the upper and lower electrical contacts of the diode. This upper layer of the insulating member is also used as a bonding surface to attach a cover over the packaged semiconductor device. The problem with fabricating such insulating members having these upper and lower conductive surfaces is that such members tend to be very small in size, typically having a diameter less than one millimeter. As noted above, the upper and lower surfaces of the insulating members must be electrically isolated one from the other, that is, sidewall portions of the conductive member must be free of traces of the conductive layer in order to prevent a short circuit between the electrical contacts of the semiconductor device. Due to the relatively small size of these insulating members, it is generally difficult to form conductive material on the upper and lower surfaces of the insulating members without also forming some conductive material along a portion of the sidewalls of the insulating members.